974 7. MERCURIALS 



cially it might be an important aspect of their use. Despite the many com- 

 parisons of the relative activities of different mercurials, very few interesting 

 correlations between structure and effectiveness have emerged. Krahe (1924) 

 found that the bacteriostatic activity of Hg++ is reduced by increasing the 

 concentration of NaCl and postulated this to be due to the formation of 

 HgClg"" and HgCl4= complexes, these being less lipid-soluble, and showed 

 that the distribution coefficient between ether and water is reduced parallel 

 with the antibacterial potency. Coleman et al. (1937) observed in the ali- 

 phatic mercurials that the antibacterial activity increases with the length 

 of the side chain. Such relationships have been found for many actions of 

 the mercurials and are probably based on differences in penetration into 

 the cells rather than to fundamental differences in action on the susceptible 

 cellular mechanisms. 



The uptake and distribution of mercurials have been well studied and 

 several facts relevant to the mechanism of their action have emerged. The 

 amount taken up in any case will depend on the relative quantities of cells 

 and mercurial present. Herzog and Betzel (1911) incubated 10 g of pressed 

 yeast (2.6 g dry weight) with various concentrations of Hg++ and found 

 the cellular Hg++ concentration to increase with the total amount of H.g++ 

 present, but the percentage taken up falls (see accompanying tabulation). 



Since there are roughly 10^'' cells in 1 g of dry yeast, these uptakes would 

 correspond to between 2 x 10* and 10® Hg++ ions/cell; they would also 

 correspond to 0.065-0.38 g Hg++/g yeast protein of molecular weight 100,000. 

 The amount of Hg++ accumulated by yeast is thus very considerable and 

 only a fraction is likely to be bound to SH groups. E. coli binds even more 

 Hg++, since Hahn and Remy (1922) found an uptake of around 0.5 g Hg++/g 

 dry weight (assuming around 75% water content) from a 3.7 mM solution. 

 McCalla and Foltz (1941) calculated that E. coli possesses around 10* bind- 

 ing sites/cell, which is close to the figure to be estimated from the uptake 

 found by Hahn and Remy. Steel (1960) claimed that a cell of E. coli con- 

 tains about 10* SH groups, but that Hg++ does not react with all of them, 



